U.S. patent number 6,371,970 [Application Number 09/470,706] was granted by the patent office on 2002-04-16 for vascular filter having articulation region and methods of use in the ascending aorta.
This patent grant is currently assigned to Incept LLC. Invention is credited to L. N. Hopkins, Farhad Khosravi.
United States Patent |
6,371,970 |
Khosravi , et al. |
April 16, 2002 |
Vascular filter having articulation region and methods of use in
the ascending aorta
Abstract
Apparatus and methods are provided for use in filtering emboli
from a vessel such as the ascending aorta, wherein a vascular
device comprises a support hoop having an articulation region
connected near a distal end of an elongated member, a blood
permeable sac affixed to the support hoop so that the support hoop
forms a mouth of the blood permeable sac, a guide wire, and a
delivery sheath. The articulation region comprises a reduced
thickness region of the support hoop that prevents kinks from
forming in the support hoop when the apparatus is contracted to its
delivery state, and curved regions that close the mouth of the sac
to prevent material escaping from the sac when the apparatus is
collapsed for removal.
Inventors: |
Khosravi; Farhad (San Mateo,
CA), Hopkins; L. N. (Buffalo, NY) |
Assignee: |
Incept LLC (San Mateo,
CA)
|
Family
ID: |
46203764 |
Appl.
No.: |
09/470,706 |
Filed: |
December 23, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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364064 |
Jul 30, 1999 |
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Current U.S.
Class: |
606/200;
606/194 |
Current CPC
Class: |
A61F
2/013 (20130101); A61F 2/0105 (20200501); A61M
2025/109 (20130101); A61M 2025/09183 (20130101); A61F
2230/008 (20130101); A61F 2230/0008 (20130101); A61F
2002/018 (20130101); A61B 2017/2212 (20130101); A61M
2025/1052 (20130101); A61F 2/011 (20200501) |
Current International
Class: |
A61F
2/01 (20060101); A61M 029/00 () |
Field of
Search: |
;606/200,191,194 |
References Cited
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|
Primary Examiner: Jackson; Gary
Attorney, Agent or Firm: Fish & Neave Pisano; Nicola
A.
Parent Case Text
REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent
application Ser. No. 09/364,064 filed Jul. 30, 1999.
Claims
What is claimed is:
1. Apparatus suitable for filtering emboli comprising:
an elongated member having a distal region;
a support hoop attached to the distal region, the support hoop
having an articulation region; and
a blood permeable sac affixed to the support hoop so that the
support hoop forms a distally-facing mouth of the blood permeable
sac;
a guide wire slidably attached to the elongated member; and
a delivery sheath having a proximally-facing cavity for accepting
the elongated member, support hoop and blood permeable sac, and a
lumen extending through the cavity to permit the guide wire to pass
therethrough.
2. The apparatus of claim 1, wherein the blood permeable sac
comprises a biocompatible material.
3. The apparatus of claim 2, wherein the biocompatible material
comprises a material chosen from a list consisting of polyethylene,
polypropylene, polyester, polyurethane and nylon.
4. The apparatus of claim 3, wherein the blood permeable sac
comprises a plurality of pores, each one of the plurality of pores
having a diameter in a range of 20 to 400 microns.
5. The apparatus of claim 1, wherein the support hoop comprises a
super-elastic material.
6. The apparatus of claim 1, wherein the support hoop comprises a
wire having a thickness that tapers to a minimum thickness at the
articulation region.
7. The apparatus of claim 1 wherein the elongated member abuts
against an interior surface of the cavity so that distal
translation of the elongated member is transmitted to the delivery
sheath.
8. The apparatus of claim 1, wherein the apparatus has a deployed
state, wherein the support hoop engages an interior wall of a
patient's vessel, and a delivery state, wherein the apparatus has a
contracted configuration to permit insertion of the elongated
member, support hoop, and blood permeable sac within the delivery
sheath.
9. The apparatus of claim 8, wherein the support hoop folds at the
articulation region when the apparatus is contracted to the
delivery state.
10. The apparatus of claim 8, wherein the mouth of the blood
permeable sac is closed when the apparatus is in the contracted
configuration, thereby preventing emboli from escaping from the
blood permeable sac.
11. The apparatus of claim 10 wherein opposite sides of the support
hoop close towards one another when the apparatus is contracted to
its contracted configuration.
12. The apparatus of claim 1, wherein the delivery sheath further
comprises a radiopaque band.
13. The apparatus of claim 1, wherein the support hoop further
comprises a radiopaque band.
14. A method of trapping emboli or thrombus during a medical
procedure, the method comprising:
providing apparatus comprising an elongated member, a support hoop
having an articulation region coupled to the elongated member, a
blood permeable sac affixed to the support hoop so that the support
hoop forms a distally-facing mouth of the blood permeable sac, a
guide wire slidably attached to the elongated member having a
distal region with a stop, and a delivery sheath having a cavity
for accepting the elongated member, support hoop and blood
permeable sac;
advancing the guide wire to a desired location within a patient's
vessel;
positioning the elongated member, support hoop, and blood permeable
sac in a contracted delivery state within the delivery sheath;
advancing the elongated member and delivery sheath over the guide
wire until the delivery sheath contacts the stop; and
with the guide wire held stationary, withdrawing the elongated
member to withdraw the support hoop from the cavity so that the
apparatus expands to a deployed state wherein the support hoop
seals against the vessel wall.
15. The method of claim 14 further comprising:
performing the medical procedure, the apparatus catching emboli
released when the medical procedure is performed;
advancing the elongated member over the guide wire to return the
apparatus to a collapsed configuration within the cavity of the
delivery sheath; and
removing the apparatus from the patient's vessel.
16. The method of claim 14, wherein advancing the elongated member
and delivery sheath further comprises advancing the elongated
member and delivery sheath to a location within the patient's
ascending aorta proximal of the aortic valve, so that the apparatus
is distal of the brachiocephalic trunk in the deployed state.
17. The method of claim 14 wherein advancing the elongated member
and delivery sheath further comprises advancing the elongated
member and delivery sheath against a direction of blood flow
through the patient's vessel.
18. The method of claim 15, wherein returning the apparatus to a
collapsed configuration within the delivery sheath channel
comprises folding the support hoop at the articulation region to
close the mouth of the blood permeable sac.
19. Apparatus suitable for filtering emboli comprising:
an elongated member having a distal region;
a support hoop attached to the distal region, the support hoop
having an articulation region;
a blood permeable sac affixed to the support hoop so that the
support hoop forms a distally-facing mouth of the blood permeable
sac;
a guide wire slidably attached to the elongated member; and
a delivery sheath having a proximally-facing cavity for accepting
the elongated member, support hoop and blood permeable sac.
20. The apparatus of claim 19 further comprising a lumen extending
through the cavity to permit the guide wire to pass therethrough.
Description
FIELD OF THE INVENTION
The present invention relates to apparatus and methods for
filtering or removing matter from within the vascular system. More
particularly, the present invention provides a low profile
self-expanding vascular device useful in the ascending aorta for
capturing emboli generated during interventional procedures.
BACKGROUND OF THE INVENTION
Percutaneous interventional procedures to treat occlusive vascular
disease, such as angioplasty, atherectomy and stenting, often
dislodge material from the vessel walls. This dislodged material,
known as emboli, enters the bloodstream, and may be large enough to
occlude smaller downstream vessels, potentially blocking blood flow
to tissue. The resulting ischemia poses a serious threat to the
health or life of a patient if the blockage occurs in critical
tissue, such as the heart, lungs, or brain.
The deployment of stents and stent-grafts to treat vascular
disease, such as aneurysms, also involves the introduction of
foreign objects into the bloodstream and may result in the
formation of clots or release of emboli. Such particulate matter,
if released into the bloodstream, also may cause infarction or
stroke.
Numerous previously known methods and apparatus have been proposed
to reduce the risk of embolism. U.S. Pat. No. 5,833,644 to
Zadno-Azizi et al., for example, describes the use of
balloon-tipped catheter to temporarily occlude flow through a
vessel from which a stenosis is to be removed. Stenotic material
removed during a treatment procedure is evacuated from the vessel
before the flow of blood is restored. A drawback of such previously
known systems, however, is that occlusion of antegrade flow through
the vessel may result in damage to the tissue normally fed by the
blocked vessel.
U.S. Pat. No. 5,814,064 to Daniel et al. describes an emboli filter
system having a radially expandable mesh filter disposed on the
distal end of a guide wire. The filter is deployed distal to a
region of stenosis, and any interventional devices, such as
angioplasty balloons or stent delivery systems, are advanced along
the guide wire. The filter is designed to capture emboli generated
during treatment of the stenosis while permitting blood to flow
through the filter. Similar filter systems are described in U.S.
Pat. No. 4,723,549 to Wholey et al., and U.S. Pat. No. 5,827,324 to
Cassell et al.
One disadvantage of radially expandable filter systems such as
described in the foregoing patents is the relative complexity of
the devices, which typically comprise numerous parts. Connecting
more than a minimal number of such parts to a guide wire generally
reduces the ability of the guide wire to negotiate tortuous anatomy
and increases the profile of the device in its delivery
configuration. Moreover, such filter devices are generally
incapable of preventing material from escaping from the filter
during the process of collapsing the filter for removal.
International Publication No. WO 98/39053 describes a filter system
comprising an elongated member, a radially expandable hoop and a
cone-shaped basket. The hoop is affixed to the elongated member,
and the cone-shaped basket is attached to the hoop and the
elongated member so that the hoop forms the mouth of the basket.
The filter system includes a specially configured delivery catheter
that retains the mouth of the basket in a radially retracted
position during delivery.
While the filter system described in the foregoing International
Publication reduces the number of components used to deploy the
cone-shaped basket, compared to the radial strut-type filter
elements described hereinabove, it too has drawbacks. Chief among
these, it is expected that it will be difficult to reduce the
diameter of the radially expandable hoop to its retracted position.
In particular, as the hoop is contracted through smaller radii of
curvature, the stiffness of the hoop is expected to increase
dramatically. This increased stiffness prevents the hoop from being
contracted more tightly and is expected to result in a large
delivery profile.
In view of the foregoing disadvantages of previously known
apparatus and methods, it would be desirable to provide a vascular
device, e.g., for use as a vascular filter in the ascending aorta,
that, overcomes such disadvantages, and employs few components.
It also would be desirable to provide a vascular device that is
capable of being contracted to a small delivery profile.
It further would be desirable to provide a vascular device that is
capable of being advanced into position from the downstream
direction of blood flow.
It still further would be desirable to provide a vascular device
that reduces the risk of emboli or thrombus removed from the vessel
wall escaping from the device when the device is collapsed and
removed.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention
to provide a vascular device, e.g., for use as a vascular filter in
the ascending aorta, that overcomes disadvantages associated with
previous vascular filters and thrombectomy/embolectomy devices, and
employs few components.
It is another object of the present invention to provide a vascular
device that is capable of being contracted to a small delivery
profile.
It is yet another object of the present invention to provide a
vascular device that is capable of being advanced into position
from the downstream direction of blood flow.
It is a further object of this invention to provide a vascular
device that reduces the risk of emboli or thrombus removed from the
vessel wall escaping from the device when the device is collapsed
and removed.
These and other objects of the present invention are accomplished
by providing a vascular device suitable for use as a vascular
filter in the ascending aorta that comprises a blood permeable sac
affixed at its perimeter to a support hoop having an articulation
region. The support hoop is attached in a distal region of an
elongated member, such as a guide wire, and supports a
distally-oriented mouth of the sac when the device is deployed in a
vessel. In accordance with the principles of the present invention,
the support hoop includes a reduced-thickness articulation region
that enables the support hoop to be contracted to very small radii
of curvature without the problems of increased stiffness and
kinking of previously known devices. The vascular device may
therefore be used with delivery sheaths having diameters as small
as 3 Fr.
The support hoop preferably also has a curved profile that prevents
the articulation region, when folded, from damaging the wall of the
vessel. The curved profile also permits the device to effectively
contact the walls of the vessel and reduce emboli or thrombus
removed from the vessel wall from bypassing the sac. The
articulation region, when combined with a support hoop having a
curved profile, causes the sides of the support hoop to fold
inwards towards one-another when the vascular device is collapsed
into a sheath for removal. This, in turn, closes the mouth of the
sac and reduces the potential for emboli or thrombus to be released
from the vascular device during removal.
Methods of using the vascular device of the present invention are
also provided, particularly in the context of a vascular filter
placed in the ascending aorta.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects and advantages of the present invention
will be apparent upon consideration of the following detailed
description, taken in conjunction with the accompanying drawings,
in which like reference characters refer to like parts throughout,
and in which:
FIGS. 1A and 1B are, respectively, a side sectional side of a
previously known vascular device contracted within a delivery
sheath and an end view of that vascular device deployed in a
vessel;
FIGS. 2A and 2B are, respectively, a perspective view of a vascular
device constructed in accordance with the principles of the present
invention in a deployed state, and a detailed view of the
articulation region of the device of FIG. 2A;
FIG. 3 is a perspective view of the vascular device of the present
invention in a folded configuration, prior to removal;
FIG. 4 is a plan view of the vascular device of FIG. 2A;
FIGS. 5A and 5B are, respectively, side sectional views of an
embodiment of the vascular device of the present invention in the
contracted state and in the deployed state that is suited for use
as a vascular filter in the ascending aorta; and
FIGS. 6A-6C are side sectional views depicting a method of
deploying, using and retrieving the vascular device of FIGS. 5 in
the ascending aorta;
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1A and 1B, some of the disadvantages associated
with previously known vascular devices, such as the emboli filters
described in the above-mentioned International Publication WO
98/39053, are described. Vascular filter comprises guide wire 10
having hoop 12 coupled to its end. Filter sac 14 is affixed to hoop
12, so that when delivery catheter 16 is retracted proximally and
guide wire 10 is held stationary, hoop 12 radially expands to
contact the walls of a vessel.
As described hereinabove, one difficulty with such vascular filters
is that the hoop used to support the filter sac experiences
increased stiffness when contracted to small diameters, i.e., due
to the sharp directional change at the tip of the hoop, thereby
limiting the minimum delivery profile achievable for such
instruments. Although this effect may be reduced by decreasing the
thickness of the wire employed in hoop 12, at the point at which
the wire becomes sufficiently thin to accommodate the bending
stresses, the wire is too thin to effectively radially expand and
urge the filter sac into engagement with the vessel wall.
On the other hand, as shown in FIGS. 1A and 1B, the bending
stresses imposed upon the hoop of such previously known devices, if
drawn within a delivery catheter, may be sufficiently high to
result in the formation of kink 18 at the tip of the hoop. This
"kinking" effect becomes more severe in sheaths having a small
inner diameter. Thus, for example, applicant has observed that when
sheaths having inner diameters of 0.035" or smaller are used, a
hoop of nitinol or multi-strand nitinol cable having a diameter of
0.0055" will form kink 18. Kink 18 in turn may apply relatively
high localized pressure and friction against wall 17 of sheath 16,
thereby making the vascular filter difficult to deploy. In
particular, the kink may impale wall 17 of delivery sheath 16 and
may make it difficult or impossible to deploy the vascular filter,
especially in tortuous anatomy.
In addition, when the filter is subsequently deployed in vessel V,
as shown in FIG. 1B, kink 18 may deform the pre-formed shape of
hoop 12, impairing the ability of the filter to seal against the
walls of vessel V. This may in turn lead to the presence of gaps G
between the perimeter of the hoop and the vessel wall, depending
upon the severity of the kink. Consequently, emboli may pass
through the gaps with antegrade flow and significantly reduce the
efficacy of the filter. Additionally, kink 18 may be sufficiently
sharp to damage or dissect the wall of vessel V when the filter is
deployed.
The vascular device of the present invention solves the
above-described disadvantages, providing a vascular device,
suitable for use as a vascular filter in, for example, the
ascending aorta, with a self-expanding support hoop that is
sufficiently thick to radially expand and urge a blood permeable
sac into engagement with the vessel wall, but which includes an
articulation region that overcomes the problems associated with
kinking. In particular, the vascular device of the present
invention includes a reduced thickness articulation region and a
pre-formed curved profile that avoids the difficulties of
previously known systems while providing a high degree of efficacy
in capturing emboli or thrombus, and ease of deployment and
retrieval.
Referring now to FIGS. 2A and 2B, vascular device 20 constructed in
accordance with the principles of the present invention,
illustratively an embolic filter, comprises guide wire 22, support
hoop 24 having articulation region 26, and blood permeable sac 28
affixed to support hoop 24. Sac 28 is coupled to support hoop 24 so
that the support hoop forms an opening for the sac. Support hoop 24
preferably is connected to guide wire 22 near distal end 23 of the
guide wire.
Sac 28 preferably is constructed of a thin, flexible biocompatible
material, such as polyethylene, polypropylene, polyurethane,
polyester, polyethylene tetraphlalate, nylon or
polytetrafluoroethylene, or combinations thereof, and includes
openings or pores 30 that permit blood cells to pass through the
sac substantially unhindered, while capturing any larger emboli
that may be released during a procedure such as angioplasty or
stent placement. In a preferred embodiment, sac 28 has openings or
pores 30 in a range of about 20 to 400 microns in diameter, and
more preferably, about approximately 80 microns. These pore sizes
will permit red blood cells (which have a diameter of approximately
5 microns) to easily pass through the sac. If sac 28 comprises a
woven material, such as formed from the above-mentioned polymers,
the pore size of the sac may be determined as a function of the
pattern and tightness of the weave.
Support hoop 24 comprises a hoop having a circular or rectangular
cross-section that is formed of a super-elastic material, such as a
nickel-titanium alloy ("nitinol"). During deployment and retrieval
of vascular device 20, described hereinafter, support hoop 24 folds
in half and collapses to fit within a small diameter delivery
sheath. When vascular device 20 is in a deployed state, as depicted
in FIG. 2A, support hoop 24 resumes its pre-formed shape. Support
hoop 24 preferably comprises nitinol wire, although it may also be
formed from a multistrand nitinol cable, or other super-elastic
material.
In accordance with the principles of the present invention, support
hoop 24 includes one or more reduced-thickness articulation regions
26 and curved regions 34. As depicted in FIG. 2B, articulation
region 26 includes a region having reduced thickness t.sub.1
compared to thickness t of the remainder of support hoop 24.
Articulation region 26 and curved regions 34 enable support hoop 24
to fold with a pre-determined shape when vascular device 20 is
collapsed to a contracted state for delivery or retrieval.
In FIG. 2B, articulation region 26 is depicted as a localized
reduction in the thickness of support hoop 24, as may be achieved
using conventional grinding or etching processes. Alternatively,
support hoop 24 may be continuously tapered along its
circumference, so that articulation region 26 results from a more
gradual reduction in the wall thickness of the support hoop.
Tapering support hoop 24 may permit greater flexibility in the
vicinity of articulation region 26, thus enabling support hoop 24
to fold more easily at the articulation region. Such tapering of
the thickness of the support hoop along a portion of its
circumference also may reduce the potential for stress-induced
fracture typically associated with abrupt changes in diameter.
In a preferred embodiment of the vascular device 20 of the present
invention, vascular device 20 easily fits within a delivery sheath
having an inner diameter of 0.033", and more preferably, may be
used with a delivery sheath having an inner diameter as small as
0.026". The deployed diameter of support hoop 24 preferably is
approximately 7 mm, while guide wire 22 preferably has a diameter
of 0.014", and tapers at its distal end. The distal end of guide
wire 22 also may be tipped with a spring section, or coil tip (not
shown).
Support hoop 24 preferably is constructed of 0.0055" nitinol wire
tapered (by a grinding process) to 0.0025" at articulation region
26. Specifically, articulation region 26 preferably consists of a
length about 0.05" long and having a diameter of 0.0025", coupled
on either side to curved regions 34. Each of curved regions 34
includes of a length of wire that is tapered from a diameter of
0.055" to a diameter of 0.0025" over a length of about 0.025".
Support hoop 24 also may include radiopaque features, such as gold
or platinum bands 33, spaced at intervals around the circumference
of support hoop 24, or a coil of radiopaque material wrapped around
the support member.
With respect to FIGS. 3 and 4, additional features of vascular
device 20 are described. FIG. 3 depicts vascular device 20 of FIG.
2A in a contracted state, while FIG. 4 illustrates a directional
change in support hoop 24 preferably caused by the presence of
curved regions 34. In the embodiment depicted in FIG. 4, curved
regions 34 illustratively are configured to orient articulation
region 26 in a direction parallel to the axis of guide wire 22.
Advantageously, use of articulation region 26 and the curved
profile of support hoop 24 introduced by curved regions 34 also
cause support hoop 24 to fold in half during retrieval. As shown in
FIG. 3, support hoop 24 folds in half, effectively closing the
mouth of blood permeable sac 28 and preventing the escape of
collected emboli or thrombus. This feature also may permit the use
of a smaller or shallower sac than would otherwise be possible,
without increasing the risk of material escaping from the device
when the sac is collapsed for retrieval. Use of a smaller or
shallower sac also enables vascular device 20 to be delivered in a
smaller delivery sheath, having an inner diameter as small as
0.026" for the preferred embodiment.
Referring now to FIGS. 5A and 5B, an embodiment of the vascular
device of the present invention suited for use as a vascular filter
in the ascending aorta is described. Vascular device 50 comprises
guide wire 51 having distal end 52 with stop restraint 53, which
may be radiopaque. Elongated member 54 is rigidly attached to
linear bearing 55, which is slidably attached to guide wire 51.
Elongated member 54 therefore may be advanced over guide wire 51 to
contact internal face 62 of delivery sheath 61, and advance the
delivery sheath. Delivery sheath 61 comprises tapered end 63 having
lumen 64 through which guide wire 51 passes, and preferably also
comprises radiopaque band 65. Distally-facing support hoop 56 has
blood permeable sac 57 attached to its perimeter. Support hoop 56
is, in turn, connected to elongated member 54 at attachment point
58. Articulation region 59 and curved regions 60 of support hoop 56
enable the sides of the support hoop to fold together and become
elongated when urged within cavity 66 of delivery sheath 61 by
distal motion of elongated member 54 with guide wire 51 held
stationary, or vice versa.
With reference to FIGS. 6A-6C, a method of deploying, using and
retrieving vascular device 50 of FIGS. 5 in the ascending aorta is
described. In FIG. 6A, guide wire 51 is manipulated into position
within ascending aorta AA just proximal of aortic valve AV using
well-known percutaneous techniques, for example, based on the
position of radiopaque restraint 53 under a fluoroscope. Vascular
device 50 is disposed in its contracted state within delivery
sheath 61. The proximal end of guide wire 51 is passed through
lumen 64 of sheath 61 and through linear bearing 55, which is
rigidly attached to elongated member 54. Elongated member 54 with
attached support hoop 56 and blood permeable sac 57 then is
slidably advanced over guide wire 51. In particular, linear bearing
55 contacts internal face 62 of sheath 61 and advances delivery
sheath 61 and vascular device 50.
Vascular device 50 is advanced until it contacts restraint 53 at
distal end 52 of guide wire 51. Restraint 53 prevents further
distal motion of sheath 61 with respect to guide wire 51. The
location of vascular device 50 may be verified using, for example,
the position of radiopaque band 65 under a fluoroscope, so that
vascular device 50 lies within ascending aorta AA proximal of
aortic valve AV, but distal of brachiocephalic trunk BT.
Referring now to FIG. 6B, with vascular device 50 in position,
elongated member 54 is retracted proximally while guide wire 51 and
sheath 61 are held stationary. Alternatively, elongated member 54
may be held stationary while guide wire 51 and delivery sheath 61
are advanced (in this case, distal end 52 of guide wire 51 is not
initially advanced as far and lies just proximal of aortic valve AV
only after deployment of vascular device 50). In either case, when
vascular device 50 is no longer confined within delivery sheath 61,
support hoop 56 expands to seal against the walls of the ascending
aorta AA. Blood continues to flow unimpeded through ascending aorta
AA in direction D. Emboli generated upstream (distal) of vascular
device 50 by, for example, interventional instruments, such as
angioplasty catheters, atherectomy devices, or stent delivery
systems, are captured within sac 57.
With respect to FIG. 6C, once the interventional procedure is
complete and generated emboli have been captured within sac 57,
elongated member 54 is advanced distally while guide wire 51 and
delivery sheath 61 are held stationary. The sides of support hoop
56 collapse together to close the mouth of sac 57 (see FIG. 3).
Additional distal advancement of member 54 urges support hoop 56
and sac 57 at least partially within cavity 66 of sheath 61. As
depicted in FIG. 6C, only a portion of support hoop 56 near
articulation region 59 and a distal portion of sac 57 extend out of
delivery sheath 61. Guide wire 51 is then retracted proximally.
Restraint 53 contacts the distal face of sheath 61, which in turn
contacts bearing 55 at internal face 62 and causes the whole of
vascular device 50 with any trapped emboli to be withdrawn
proximally.
As will of course be understood by those of skill in the art of
catheter design, FIGS. 5 and 6 have not been drawn to scale to
clarify certain aspects of the structure of the preferred
embodiments. For example, the diameter of delivery sheath 61 is
approximately an order of magnitude smaller than either the inner
diameter of the ascending aorta or the full deployed height of
support hoop 57.
Although preferred illustrative embodiments of the present
invention are described above, it will be evident to one skilled in
the art that various changes and modifications may be made without
departing from the invention. It is intended in the appended claims
to cover all such changes and modifications that fall within the
true spirit and scope of the invention.
* * * * *